The present invention relates to a video signal recording apparatus, a video signal reproducing apparatus and a video signal recording and reproducing apparatus having a function of skipping commercial messages (abbreviated to CM hereinafter) and reproducing TV programs only in reproduction modes such as follow-up reproduction, cache recording/reproduction and variable-speed reproduction from a randomly accessible storage medium such as a hard disc on which video and audio signal have been recorded.
Here, the follow-up reproduction is a technique for reproducing already recorded portions while recording a TV program.
The cache recording/reproduction is a technique for sequentially recording video/audio information in a bitstream recording area for a certain period with overwriting new information on the oldest recorded information when recording has been carried out to the last portion of the recording area and reproducing video/audio information for a certain period from the information recorded before.
There are three modes, namely, monaural, bilingual and stereophonic for audio signals to be broadcast with video signals. One of the modes is selected in accordance with a TV program to be broadcast. Video signals are broadcast with audio signals of selected audio mode.
TV programs are broadcast with CM portions. Audio modes are mostly different between TV programs and CM portions. There are video tape recorders (VTR) having a CM-cutting function in which audio modes for TV programs and CM portions are discriminated from each other so that CM portions will not be recorded based on the detected modes.
This technique for discriminating TV programs and CM portions from each other based on difference in audio mode is used in home-use VTRs because of low cost. Most CMs are broadcast in stereophonic mode. Thus, in this technique, when a broadcast TV program is in monaural or bilingual audio mode, stereophonic mode portions broadcast with the TV program are detected as CM portions, and thus the stereophonic audio mode portions will not be recorded.
Video signals are mostly recorded and reproduced by VTRs. However, a multi-functional video signal-recording/reproducing apparatus for recording/reproducing bitstreams of coded video signals on/from a storage medium such as a hard disc with high accessibility will be introduced in the near future.
The multi-functional video signal-recording/reproducing apparatus can record several TV programs at the same time because of short access time to recorded signals. The apparatus further has a follow-up reproduction function in which recording of a TV program for recording has been started is proceeding while reproduction follows up and reaches the TV program now on air.
Another type of multi-functional video signal-recording/reproducing apparatus is to record types of information such as a TV program itself and a CM portion as management data on a storage medium at portions different from video and audio information and reproduce the TV program with skipping the CM portion based on the management data.
Recording of TV programs without CM portions in home-use VTRs should avoid malfunctions which could occur due to such recording. This is because a TV program broadcast in stereophonic mode causes difficulty in discriminating the TV program from the CM portions. Thus, CM-cutting will be nonfunctional. And, if this function is erroneously set, the head portion of a TV program is detected as a CM portion, thus recording of the TV program will not start.
Such a problem also occurs for disc-recording/reproduction apparatus using a disc-like storage medium with short accessing time. This apparatus has a CM detector to detect a period of CM portions while recording TV programs. Data on the detected period of CM portions is temporary stored in a memory controlled by a microcomputer. The stored CM-period data is recorded on a certain position of a disc at time of completion of TV program-recording.
The recording of CM-period data is similar to a technique for writing management data as TOC (Table of Contents) data on a certain position of an MD (Mini Disc which is a magneto-optical disc) when recording is completed. MDs are used for audio systems that mainly record audio signals.
Known disc-recording/reproduction apparatus record CM-period data on a storage medium when recording of a TV program is completed and retrieve the management data in reproduction. The retrieved disc-management data such as CM-period data is temporary stored in a memory. The known apparatus, however, have no CM-cut or -skip function.
The known apparatus also cannot skip CMs in reproduction while recording of a TV program is proceeding, such as, in follow-up reproduction and cache reproduction/recording.